* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  width: 100vw;
  height: 100vh;
  background-color: skyblue;
  display: flex;
  justify-content: center;
  align-items: center;
}
table,
td {
  border-collapse: collapse;
}
td {
  border: 1px solid grey;
  padding: 10px;
}
table tr:nth-child(even) {
  background-color: cadetblue;
}
table tr:nth-child(odd) {
  background-color: chartreuse;
}
td.active {
  background-color: aquamarine;
}
